Civil libertarians and security officers at Logan International Airport continue to dispute findings by the Department of Homeland Security that there was no evidence of airport screeners using racial profiling to improve the results of a program that aims to detect suspicious behavior.

The American Civil Liberties Union of Massachusetts this week sent a letter to the state’s congressional delegation outlining concerns with a recent investigation by the Department of Homeland Security’s Office of Inspector General into allegations of racial profiling at Logan.

The inspector general’s report, a synopsis of which was obtained by the Globe in September, said there was no indication that Transportation Security Administration officers in Boston targeted minorities for additional screening as a way to meet quotas. The full report has not been released.

In the letter, the ACLU called for an inquiry into how the inspector general conducted its investigation, arguing the probe was inadequate for several reasons. Investigators looked only at whether managers explicitly told officers to focus on people of color, the ACLU said, not at whether officers were pulling people aside based on race or national origin.

They also focused on specific dates and times when passengers were designated for additional screening, instead of looking for patterns over several months, the ACLU said.

Finally, investigators seem to have overlooked copies of passport and driver’s license photos of passengers referred to police as a result of TSA screenings, the ACLU said.

Those pictures would have shown the “vast number of people pulled for extra screening were black, Hispanic, Dominican, Brazilian, Mexican, and Muslim,” the ACLU said.

A spokesman for the inspector general declined to comment, saying the office “does not confirm or deny any audit, inspection, or investigation.” Matthew Brelis, spokesman for the Massachusetts Port Authority, which operates Logan, said, “We’ve consistently said there’s no place for racial profiling in airport security.”

Allegations of racial profiling at Logan surfaced in August 2012 after eight TSA officers expressed concerns to the ACLU of Massachusetts about colleagues who, they said, were seeking out minorities during security checks. Previously, more than 30 officers had filed internal complaints about the practice, the ACLU said.

The focus of the complaints was the behavior-detection program, which refers suspicious passengers for additional screening based on body language, responses to questions, and unusual actions like wearing a heavy coat in the summer.

Managers at Logan demanded that a high number of passengers be stopped for additional screening as a way to increase referrals to State Police and show that the behavior detection program produced results, the officers told the ACLU. That led some of their colleagues to focus on minorities in the belief they would be more likely to have immigration issues or arrest warrants, they said.

Logan was the first airport in the nation to institute a behavior-detection program, in 2003. The TSA implemented a similar effort, called Screening of Passengers by Observation Techniques, or SPOT, in 2007. It is now used in 176 airports nationwide.

In a 99-page report released this week on the behavioral program, the Government Accountability Office, a watchdog agency, said five of 25 behavior- detection officers interviewed at airports, including Logan, said profiling was taking place. Seven additional officers contacted the GAO to express concern about profiling, according to the report.

Sarah Wunsch, a staff attorney for the ACLU of Massachusetts, said the GAO report backs up allegations of profiling at Logan.

“When it’s left to employees’ subjective determinations, that easily lends itself to what is in fact stereotyping based on racial, ethnic, or religious groups,” she said. “This is an issue that’s not going to go away.”

The GAO found no scientific evidence the behavior-detection program can identify people who pose risks to aviation security. The report recommended that Congress consider this lack of evidence before making future funding decisions.

The TSA’s administrator, John Pistole, disputed that the program is ineffective at a House Homeland Security subcommittee hearing on Thursday. He cited a 2011 TSA study conducted with the American Institutes for Research that found a high-risk traveler is nine times more likely to be identified using behavioral detection, as opposed to random screening.

An independent committee of members of the academic, law enforcement, and intelligence communities agreed with the findings, he said.